1. Field of the Invention
The present invention relates to a binding device for a baler including at least one knotter and a twine needle driven by the knotter shaft driven by the baler plunger drive, a one-stop clutch for connecting the knotter shaft with the plunger drive and for intermittently driving the knotter shaft, and transmission means provided between the one-stop clutch and the knotter shaft.
2. Description of the Prior Art
Such knotters are most often used in balers for forming bales of agricultural harvest goods, but they can also be used for forming bales from paper products, paperboards, recyclable products, and the like. Generally, a plurality of knotters are arranged next to each other over the baling channel. When a bale reaches a predetermined length, the knotter secures the bale with twine loops.
All of the presently available on the market balers use a knotter the shaft of which is driven so that the drive ratio between the knotter shaft and the crank drive of the plunger is 1:1. The knot formation starts only when the plunger moves back from its compressing end position. With the return movement of the plunger, the material of the twine loop expands, with the twine being tightened by the twine needle. This, however, results in a rather high xe2x80x9clooseningxe2x80x9d of the twine with a loss of a portion of the compressed density of the bale. Other drawbacks of a conventional binding device are apparent from German Publication DE 1095044 that addresses those drawbacks. Namely, with large dimensions of bales (with a cross-section 1.2 mxc3x971.2 m and a length of 2.5 m), several knotters are used which are arranged next to each other. Therefore, production tolerances of separate knotters are added to each other and, as a result, a very fine adjustment of the knotters is necessary. In addition, the twine needles can become damaged during a following compression, as the needle partially remains in the baling channel when a next compression cycle starts.
The solution according to DE 10 95 044 is based on an idea to change the drive ratio between the plunger stroke and a revolution of the knotter shaft to 1:2, so that the knot formation takes place in the compressing end position of the plunger (at front dead point in the compression direction), i.e., is performed in half time. With this, the input drive shaft of the one-stop clutch is driven with a double rotational speed in comparison with the speed of an input drive shaft as opposed to the speed of the input drive shaft of the one-step clutch being equal to the input drive shaft speed when the drive ratio is 1:1. However, an expansive switch mechanism becomes necessary for controlling the operation of the one-stop clutch in dependence on the operation of the plunger. In addition to a complex and prone to failure design of the kinematic mechanism, the disclosed binding device has two other big drawbacks. As the knot formation takes place at the dead point, very high forces acting on the twine are generated. Therefore, the twine loop should be able to withstand the expansion force of the compressed bale that are produced by the plunger in its compressing end position. In addition, the drive or transmission ratio 1:2 is determined by the system and cannot be changed.
Because of the foregoing drawbacks, the solution according to DE 10 95 044 did not find a practical application. Despite numerous attempts (see, e.g., DE 10 69 419) to find a solution of the above-discussed problem, no solution, which could have a practical application, was found.
Accordingly, an object of the invention is to provide an improved binding device for a baler and including simple means for controlling operation of the knotter shaft.
These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing in the transmission means, means that would insure that for one complete revolution of the one-stop clutch, the knotter shaft also performs one complete revolution but with a speed twice of that of the one-stop clutch.
According to the present invention, the engagement of the knotter shaft takes place, in the power flow direction, after the one-stop clutch. As a result, the one-stop clutch can be driven with a transmission ratio of 1:1 with respect to the crank drive of the plunger, without a need in additional control means for controlling the operation of the one-stop clutch. The actuation of the one-stop clutch is controlled by a measurement wheel, which determines or detects the length of the formed bale, independent from the plunger operation, as in the conventional balers. Therefore, the start of the rotation of the knotter shaft need not be changed in comparison with conventional balers, but the twine needle moves in and out of the baling channel with a greater speed. The transmission ratio determines the speed of the twine needle movement in and out of the baling channel and can be varied. Thus, according to the selected transmission ratio, the binding can start after the plunger dead point or in the dead point. However, the further away from the dead point the binding starts, the greater would be the twine loosening and the loss of the compressed density of the formed bale.
Further advantages of the present invention consists in that:
The twine needle leaves the baling channel earlier and, as a result, danger of the needle being damaged during a following compression stroke of the plunger is eliminated;
The bale shape and its compression density are improved, as no or smaller twine loosening takes place;
The twine needle/plunger adjustment can be more reliably selected because the plunger has a greater overrun with respect to the twine needle;
Use of larger adjustment tolerances becomes possible; and
The inventive design requires use of only small number of additional components, with other components remaining the same as in the conventional constructions.
In a preferred embodiment of the present invention, the one-stop clutch drives the knotter shaft or a connecting shaft via a tooth wheel or face gear segment and a tooth wheel or pinion mounted on the knotter shaft or the connecting shaft. By selecting transmission ratio, engagement length, and engagement time period, the time of the knot formation can be so selected that the bale is tied in the vicinity of the dead point, i.e., at a point when the plunger only starts to withdraw from its compressing end position. Basically, it is also possible to provide an arrangement with which the transmission means includes a gear unit arranged between the knotter shaft and the one-stop clutch and an additional clutch for connecting the gear unit with the knotter shaft and providing for a complete revolution of the knotter shaft upon actuation of the one-stop clutch.
The present invention expands the variation possibilities of the controlling operation of the binding device without electronic measurement of the bale length and actuation of the one-stop clutch.
To reduce the weight of the device, at least some of the components of the needle drive, the one-stop clutch and the transmission means, are formed of a light metal.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.